I found out about this through Allspark.com. Apparently there will be a SW Crossovers Transformers figure, "Star Wars Transformers Class III" that will have four modes: Anakin Skywalker, Darth Vader, Republic Attack Cruiser and Imperial Star Destroyer. It is set to be released this year.

This was mentioned in a magazine called Toy News, and a photo of the page detailing this specifically can be found on Rebelscum.com, here.

I'm making a prediction. Switching between the two robot and alt modes will involve flipping the toy around to the other side. Vader will be on the back of Anakin, while the Star Destroyer will be on the bottom side of the Republic Cruiser. There will be transforming between the two modes, obviously, but that will be one of the steps. I also bet that you push one bridge down to push the other one up. Lastly, the robot parts not being used will transform into a "cape" that is basically the other ship. Anakin with a Star Destroyer on his back, Vader with a Republic Cruiser on his.

sometimes engineering two good modes when one they have look like specific licenced things is trickey enough, ( especially when one more is a human) but 4 modes that need to drastically different . . . This will be quiet the engineering challenge.